For high areal density magnetic recording, one of the requirements is to have lower fly height in order to have better signal to noise ratio for better head performance. However, there are many reliability problems associated with this low fly height. Problems such as thermal pole tip protrusion, resulting from thermal mismatch between the alumina and pole material during the writing process will create a head disk interface problem and eventually damage the read head.
One way to reduce thermal pole tip protrusion is to have a better heat dissipation mechanism so that heat generated by the coil during the writing process can be transferred to the substrate to avoid heat accumulation. On the other hand, it is required to have a small shield that only covers the read sensor (to reduce external field disturbance) in order to improve the overall reader performance. Thus there is a problem of how to make a small active shield have good heat dissipation.
A routine search of the prior art was performed with the following references of interest being found:
In U.S. Pat. No. 6,239,954 Segar et al. disclose a non-magnetic element over the bottom shield to detect and cancel thermal changes in the read head. In U.S. Pat. No. 6,556,389 Boutaghou et al. describe a thermal barrier of zirconia over the magnetic read head element to dissipate heat while Inoue et al. show a AIN heat sink over a bottom shield in US Patent 2002/0081778.